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A famous German World War II bomber nicknamed "the flying pencil" has spent decades submerged in the English Channel after being shot down in the Battle of Britain. Now, divers are braving dangerous tides to bring it to the surface.

British officials on Friday announced a complex salvage operation just off the Kent coast in southeastern England to rescue the only known surviving example of the German Dornier Do 17 bomber. The operation is under way and if all the preparations go well, the plane will be lifted from the water in three or four weeks.

But the director of London's RAF Museum, which has been raising money for the salvage, cautioned that the recovery would be risky -- divers will only be able to work for 45 minutes at a time because of perilous tides, and they face other challenges.

"We are not guaranteed success," Peter Dye said. "There have been previous aircraft recovery projects that didn't go so well, cases where the structure has disintegrated on retrieval. When it breaks the surface, gravity and the laws of mechanics come into play, so we very much hope the frame we've constructed will support that structure."

Corrosion is another obstacle that could spoil the procedure, he said.

RAF Museum officials also said the challenging salvage will be the biggest recovery of its kind and they hope to one day display the Do 17, an aircraft nicknamed "the flying pencil" because of its narrow fuselage, at the museum. The museum has already raised the estimated $930,000 that will be needed for the lifting phase of the operation, with the help of a substantial donation from the National Heritage Memorial Fund, and funds are being raised for the conservation effort.

The wreck is submerged in about 60 feet of water. The plane was shot down during the 1940 Battle of Britain, a months-long clash over the skies of Britain that saw RAF fighters engaged in a colossal life-or-death struggle with the German Luftwaffe.

Experts said the bomber, discovered by divers five years ago, is remarkably undamaged despite the passage of time.

Dye said the plane would be exhibited next to a Hawker Hurricane fighter that had also been shot down during the battle.

"We feel it's important that they be exhibited side by side," he said, pointing out that two German airmen died in the Dornier. "With time, we recognize that young men died on both sides, which is why we don't intend to restore it. We will conserve it and place it on exhibition alongside the wreck of a Hurricane shot down at much the same time in which a British pilot died."

Museum officials say the Dornier was shot down on Aug. 26, 1940, at the height of the Battle of Britain. It was forced to make an emergency landing on the Goodwin Sands at low tide after it came under attack by British fighter planes. It touched down safely but then sank -- two of the crewmen were captured alive and taken prisoner; the other two died. Their bodies were found washed ashore later.

If the plane is lifted from the Channel without damage, it will still be several years before it can be put on display. It will be packed in a special chemical gel and plastic sheeting to protect it from damage caused by exposure to air, then taken by road to the RAF Museum in Cosford for extensive conservation treatment expected to take two or three years.

During that time, it will be placed in "hydration tunnels" so that chemicals and salts that accumulated during 70 years underwater can be gently washed away. After that, steps must be taken to stabilize corrosion within the plane itself. Once this is done, the plane should be ready to be put on exhibit at the RAF Museum in London.